Possible in-vivo transfer of β-lactamase TEM-3 from Klebsiella pneumoniae to Salmonella kedougou

Salmonella kedougou BM2659 was isolated from the stools and a blood culture of a patient and Klebsiella pneumoniae BM2657 and S. kedougou BM2658 were isolated later from the stools of the same patient. Strains BM2657 and BM2658 had identical resistance phenotypes, to beta-lactams, aminoglycosides and tetracycline, due to the presence of the same genes, blaT, aacA4 and tetC, respectively. Oligotyping indicating that beta-lactam resistance in these strains was encoded by blaT-3 and synthesis of TEM-3 was confirmed by isoelectric focusing. In BM2657 and BM2658, the resistance characters were located on Inc7 or M self-transferable plasmids with indistinguishable EcoRI and HindIII restriction patterns. Southern hybridization of plasmid DNA of these strains with probes pCFFO4, the prototype plasmid encoding TEM-3, genes blaT, aacA4 and tetC gave identical patterns. S. kedougou BM2658 and BM2659 had identical biotypes and serotypes but BM2659 was susceptible to all the study antibiotics. These observations suggest possible transfer, in the digestive tract, of a plasmid encoding TEM-3 beta-lactamase from K. pneumoniae BM2657 to S. kedougou BM2659.